1. Field of the Invention
The present invention relates to an apparatus and method for making frozen confections. Although suitable for all types of frozen confections, the apparatus is described in connection with soft-serve sorbets and yogurts, for which it has particular advantages.
2. Description of the Related Art
Typical related art commercial frozen confection machines contain four integrated systems; an insulated compartment for storing liquid food substances; a gas circuit for providing an edible gas for mixture with the liquid food substances; a production unit for making a frozen confection from the mixture of liquid and gas; and a refrigeration circuit for cooling both the insulated compartment and the production unit.
The storage compartment is typically connected to the production unit by a tube which defines a food path. In order to minimize bacterial contamination within the system, it is desirable to minimize the length of the food path and the number of components through which the liquid food substance must pass before it is frozen in the production unit.
The gas circuit is provided to mix gas with the liquid food substance which typically serves two functions. First, it inflates the liquid food substance to increase the volume of frozen end product that can be produced from a given volume of liquid food substance. Second, it decreases the density of the frozen end product which leads to a smoother texture in the frozen end product.
The production unit, which may be cooled by freon circulated by the refrigeration circuit, typically contains a cylindrical tube for receiving liquid food substance therein. Augers disposed within the tube churn the liquid food substance to mix it with the gas and to expose the mixture to the cooled walls of the cylinder, thereby freezing the mixture.
As the liquid food substance cools in the production unit, its ability to absorb and be become emulsified with the gas decreases. Thus, if a critical temperature is reached before the gas and liquid are fully emulsified, pockets of gas will form within the cylinder. When a dispensing valve on the cylinder is opened, these pockets of gas may "blow-out", spewing food product through the valve. In addition, product quality may be poor if full emulsification has not occurred.
In order to prevent blow-outs and to provide a fully emulsified product, the cooling rate may be decreased. However, the slower the mixture cools, the larger the crystal size in the end product. Since smaller crystal size results in a smoother textured end product, a fast cooling rate is desirable.
Some related art devices separately inject the liquid and gas into the production unit, and some include premixing units or saturators in the food path for mixing the liquid and gas before it enters the cooled environment of the production unit. A drawback of premixing units is that they provide additional nooks and crannies within the food path that may trap food particles and thereby lead to bacterial growth.
Thus, a major drawback of related art devices is their inability to rapidly cool a liquid and gas mixture to achieve small crystal structure, while at the same time ensuring that the gas and liquid become fully emulsified.
While related art devices may use pumps to convey liquid food substance into a production unit, they may not be designed to always maintain a positive pressure in the system during use. Rather, they may fluctuate between positive pressure and atmospheric pressure, or may substantially operate at atmospheric pressure. If the pressure in the system falls to atmospheric pressure, contaminants may enter the system leading to bacterial growth. Thus, more frequent cleaning may be necessary to maintain a bacteria free environment.
Further, many related art devices are open system devices wherein liquid food product is poured into an opened holding reservoir or is otherwise exposed to air from the surrounding atmosphere. Such structure not only increases the possibility that bacteria and foreign particles will contaminate the food product, but also allows odors in the surrounding atmosphere to be absorbed into the food product, degrading the taste of the end product. Hospitals and other institutions that use odorous sanitizing chemicals avoid frozen confection machines in their cafeterias for this very reason.
An object of the present invention is to provide a frozen confection apparatus and method that rapidly cools a liquid and gas mixture to ensure small crystal size.
Another object of the present invention is to provide an apparatus and method that ensures full emulsification of the liquid food substance and the gas even when rapid cooling occurs in the production unit.
A further object of the present invention is to provide an apparatus and method for premixing the liquid and the gas while at the same time minimizing locations within the food path where food particles may become lodged.
An additional object of the present invention is to provide an apparatus and method that ensures homogeneous mixing of liquid food substance and gas and prevents the occurrence of blow-outs.
In addition, it is an object of the present invention to provide a frozen confection apparatus and method that maintains a positive pressure within its food path to discourage the entry of contaminants.
An even further object of the present invention is to provide a frozen confection apparatus and method that is an hermetically sealed closed system in order to prevent either contaminants to enter the system or odors from the surrounding atmosphere to be absorbed into the food product.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.